| 摘要 |
A direct drive drawworks has a permanent magnet motor with a first set of windings and a second set of windings, a shaft extending from the permanent magnet motor such that the permanent magnet motor directly rotates the shaft, a drum connected to the shaft away from the permanent magnet motor such that the rotation of the shaft causes a corresponding rotation of the drum, and a switch cooperative with the first set of windings and the second set of windings so as to cause the sets of windings to be selectively connected in parallel or in series.
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